发现这章节，有个同学问了个UrlBlockHandler不存在的问题，老师好像是没有回答这个类变成什么类了，是在考验我们处理问题的能力吗^ ^
我现在用的是sentinel1.8.5当前最新版本了吧，我想总不能会把这个功能阉割掉吧，即使没有这个类了，应该会有差不多的类代替，随便找个的放打了BlockHandler就发现idea自动提示了一个BlockExceptionHandler 这个类，进去看了下，实现了这个类，发现基本上和老师课上的UrlBlockHandler神似，然后看了下捕捉的异常类的子类，不就是课程上的几个异常吗

@Component
public class MyBlockExceptionHandler implements BlockExceptionHandler {
    @Override
    public void handle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, BlockException e) throws Exception {
        ResponseMsg msg = null;
        if (e instanceof AuthorityException) {
            msg = ResponseMsg.builder()
                    .status(101)
                    .msg("权限错误")
                    .build();
        } else if (e instanceof DegradeException) {
            msg = ResponseMsg.builder()
                    .status(102)
                    .msg("降级限制")
                    .build();
        } else if (e instanceof FlowException) {
            msg = ResponseMsg.builder()
                    .status(103)
                    .msg("流控")
                    .build();
        } else if (e instanceof SystemBlockException) {
            msg = ResponseMsg.builder()
                    .status(104)
                    .msg("系统规则负载")
                    .build();
        } else if (e instanceof ParamFlowException) {
            msg = ResponseMsg.builder()
                    .status(105)
                    .msg("热点参数限流")
                    .build();
        }
        httpServletResponse.setHeader("Content-Type", "application/json;charet=utf-8");
        httpServletResponse.setStatus(500);
        httpServletResponse.setCharacterEncoding("utf-8");
        httpServletResponse.setContentType("application/json;charset=utf-8");
        new ObjectMapper()
                .writeValue(httpServletResponse.getWriter(), msg);
    }
}

@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
class ResponseMsg {
    private int status;

    private String msg;
}

完美实现了老师课上的内容

希望后面的同学可以借鉴